The present invention relates to a flashlight having a battery suspension system. More specifically, the battery suspension system of the present invention protects the flashlight batteries from excessive physical shock when, for example, the flashlight is bumped or dropped. Further, the present invention helps to ensure that, when the flashlight is switched to the on position, an electrically conductive path is maintained even if the flashlight is bumped or dropped.
Conventional flashlights are designed to have a substantially hollow flashlight body that provides a handle with which to grip the flashlight, and provides a housing for receiving the battery or batteries, which are the electrical power source for the flashlight. Typically, the batteries are loaded into the flashlight body end to end so as to be electrically in series. Often the flashlight will include an end cap and a head assembly, either or both of which are removably mountable to the flashlight body. The head assembly houses a lens, a reflector, and a light bulb socket into which a light bulb is mountable. In order to illuminate the light bulb, a closed electrical circuit between the batteries and the light bulb must be provided to allow electrical current to flow through the light bulb filament.
Normally, the closed electrical circuit includes the center electrode of the foremost battery mounted in the flashlight body, an electrically conductive path from this center electrode to a first terminal of the flashlight bulb, and an electrically conductive path from a second terminal of the flashlight bulb to the terminal electrode of the rearmost battery mounted in the flashlight body. The batteries are connected in series by aligning the center electrode of a rearward battery to the terminal electrode of a forward battery. A switch for interrupting the electrical circuit is disposed at some point in the circuit so that the flashlight may be turned on and off, as desired.
In an effort to secure the electrical connection between the batteries themselves, and between the interface between the batteries and the remainder of the electrical circuit, it is known to provide a conductive spring at the base of the rearmost battery and/or at the top of the foremost battery. Such a spring (or springs) acts to urge the batteries in the longitudinal direction of the flashlight body. Further, such a spring (or springs) may be somewhat effective to isolate the batteries from physical shock due to bumping or dropping of the flashlight.
Such conventional battery suspension systems, however, suffer from a number of drawbacks. For example, often there is provided only a single conductive spring at the base of the rearmost battery, while the center electrode projection of the foremost battery abuts against a non-yielding electrical contact. Such an arrangement offers only limited shock absorption, and is likely to transmit force due to shock to the center electrode projection of the foremost battery. The center electrode projection creates a load path to the battery that makes the battery particularly susceptible to damage. Such damage may cause malfunction of the flashlight or, with some batteries, may cause leakage of toxic substances.
Even when conductive springs are provided at each end of the battery stack, it is often the case that the forward conductive spring has a base diameter that substantially equals the diameter of the center electrode projection of the foremost battery. Such an arrangement concentrates any force that is transmitted to the battery onto this center electrode projection, which, as stated above, tends to be a vulnerable portion of the battery and is likely to transmit damaging forces to the battery. Moreover, because the batteries are likely to experience some radial movement when the flashlight is dropped or jostled, such a forward conductive spring is likely to slip off or otherwise lose contact with the center electrode projection of the foremost battery, interrupting the electrical circuit and causing flashlight malfunction.